Evolution - 5.1 Evolution Evidence

Question 1

Understandings:

Answer 1

1. Evolution occurs when heritable characteristics of a species change
2. The fossil record provides evidence for evolution
3. Selective breeding of domesticated animals shows that artificial selection can cause evolution
4. Evolution of homologous structures by adaptive radiation explains similarities in structure when there are differences in function
5. Populations of a species can gradually diverge into separate species by evolution
6. Continuous variation across the geographical range of related populations matches the concept of gradual divergence

Question 2

Evolution =

Answer 2

changes over time -> in living organisms = change refers to the heritable characteristics of a species (= biological evolution)

Question 3

Evolution involves a genetic changes

Answer 3

= the result of mutations or the selection of different allele combinations
–>
therefore: heritable characteristics are encoded for by genes and may occur within a population between generations as alleles

Question 4

definition for biological evoltuion:

Answer 4

cumulative changes that occur within a population between generations

simplified:
a change in the allele frequency of a population’s gene pool over successive generations

Question 5

microevolution =

Answer 5

small changes (eg cat ear shapes, colours) (and lead to the formation of a new breed/strain)

Question 6

macroevolution =

Answer 6

big changes that also result in new species and even phylum

Question 7

selective breeding

(examples on bioninja!)

Answer 7

a form of artificial selection (in which man intervenes in the breeding of species to produce desired traits in offspring)

therefore:
thing with desired trait + thing with desired trait = trait’s frequency increases throughout generations

• selective breeding = provides evidence of evolution as targeted breeds can show signif. variation in a relatively short time

Question 8

Comparative anatomy

Answer 8

Comparative anatomy of groups of organisms may show certain structural features that are similar = implying common ancestry

Question 9

Comparative anatomy - HOMOLOGOUS STRUCTURES:

Answer 9

= anotomical feathers that are similar in basic structure despite being used in diff ways
-> more similar they are between 2 species = more likely to be more closely related

HS illustrates = ADAPTIVE RADIATION = several new species rapidly diversify from an ancestral source with each new species adapted to utlitse a specific unoccupied niech

eg pentadactyl limb in diff animals (bioninja!)

Question 10

Speciation:

Answer 10

in population, in species = gene variation -> normally, varialtion = continuous and follow a normal distribution curve as the rate of change is gradual and cumulative

= the evolutionary process by which 2 related populations diverge into separate species

Question 11

Speciation - environmental effects:

(DEGREE OF DIVERGENCE)

Answer 11

If species becomes geographically split = experience different ecological conditions = overtime populations will adapt to the different conditions and gradually diverge

DEGREE OF DIVERGENCE = depends on extent of separation + time
- less = closer and recent
- more = further and longer

Question 12

genetic divergence and genetic compatibility

Answer 12

as the genetic divergence between the relation populations increases, their genetic compatibility consequently decreases

-> eventually: 2 populations will diverge to an extent where if put in the same environment = can not longer intercreeed
WHEN THIS HAPPENS:
(= no interbreed and no fertile production) = CONSIDERED TO BE SEPERATE SPECIES

therefore, speciation = the evolutionary process by which 2 related populations diverge into separate species

Question 13

Fossil evidence:

Answer 13

an example of how fossils prove evidence of evolution can be established by comparing hominin skeletons

eg
1. Australopithecus = haminin ancestor = first appeared (fossil record) approx 4 million years ago
2. (modern) homo sapiens = comparison (n) = demonstrates key evolutionary changes

Question 14

Law of Fossil Succession

Answer 14

Fossils can be dated by determining the age of the rock layer (strata) in which the fossil is found

Sedimentary rock layers develop in a chronological order, such that lower layers are older and newer strata form on top
Each strata represents a variable length of time that is classified according to a geological time scale (eons, eras, periods)

Different kinds of organisms are found in rocks of particular ages in a consistent order, indicating a sequence of development

• Prokaryotes appear in the fossil record before eukaryotes
• Ferns appear in the fossil record before flowering plants
• Invertebrates appear in the fossil record before vertebrate species

This chronological sequence of complexity by which characteristics appear to develop is known as the law of fossil succession

This ordered succession of fossils suggests that newer species likely evolved as a result of changes to ancestral species

Question 15

Transitional Fossils

Answer 15

While fossils may provide clues as to evolutionary relationships, it is important to realise that the fossil record is incomplete

1) Fossilisation requires an unusual set of specific circumstances in order to occur, meaning very few organisms become fossils

2) Only the hard parts of an organism are typically preserved, meaning usually only fragments of remains are discovered

3) With limited fossil data, it can be difficult to discern the evolutionary patterns that result from ancestral forms (‘missing links’)

Transitional fossils demonstrate the intermediary forms that occurred over the evolutionary pathway taken by a single genus
1) They establish the links between species by exhibiting traits common to both an ancestor and its predicted descendents
2) An example of a transitional fossil is archaeopteryx, which links the evolution of dinosaurs (jaws, claws) to birds (feathers)
3) As new fossils are discovered, new evolutionary patterns are emerging and old assumptions are challenged

Question 16

fossil record provides evidence when:

Answer 16

something demonstrates a change in characteristics from an ancestral

(by revealing the features of an ancestor for comparison against living decesdants)

Question 17

Cabon datings vs postassim/Argon (K/Ar)

Answer 17

Carbon-14 can be used for dating things but has a half-life 5,700 years = runs out

postassim/Argon (K/Ar) 1/2 life of 1.3 billion years

Question 18

fossil =

Answer 18

perseved remains or traces of any organism from the remote past
1. preserved remains (body fossils) = direct evidence of ancestral forms and include: teeth, shells, bones
2. traces provide indirect evidence of ancestral forms and include: footprints, toothmarks, etc

to tality of fossils = both discovered and undiscovered = refers to fossil record = shows that over time changes have occurred in the deathers of living organisms (= evolution)

Question 19

Transitional Fossils pt 2

Answer 19

Fossils can show gradual evolutionary changes with the intermediary forms that occurred over the evolutionary pathway taken by a single genus

Question 20

fossil evidence for horse ancestor

Answer 20

horse breakdown = pg 2 of booklet

Question 21

Selective Breeding

Answer 21

= shows how artificial selection can cause evolution

1) horse breeding
2) cow breeding
3) dog breeding

Question 22

Homologous structures (and common ancestors)

Answer 22

= the evolutionary relationships between groups of organisms is determined mainly by structural similarities = HS = suggests they all descended from a CA w/ that feature

Question 23

Homologous structures and adaptive radiation

Answer 23

= AR = a type of divergent evolution where a common ancestor evolves into a large number of species to occus different niches

Question 24

Homologous structures = EXAMPLE

Answer 24

Pentadactyl limb!!! the bones of the forelimb of vertebrates are composed of similar bones arranged in a comparable pattern = indicative of a common ancestry

limb = mammals, birds, amphibians, reptiles (over 300 million years ago) = EARLY LAND VERTEBRATES

Pentadactyl limb = limb with 5 fingers/toes

Question 25

Analogous Structures (bird and fly wings - analogous)

Answer 25

= they have separate evolutionary origins but are superficially similar as they both have experienced natural selection that shaped them to play a key role in flight

Question 26

Analogies =

Answer 26

are the result of convergent evolution where the environment selects for the same solution

Question 27

convergent evolution =

Answer 27

pattern of evolution in which different species evolve to resemble each other if they have similar ecological roles due to the similar selection pressures (eg shark (fish))

Question 28

divergent evolution

Answer 28

= 1+ species evolve from a common ancestor (ie speciation - eg environmental effections)

Question 29

speciation =

(members of the same species NEED to be able to interbreed and produce fertile offspring (and re genetically distinct from one another))

Answer 29

the process by which new species form whereby the new species is genetically distinct and unable to reproduce successfully with the ancestral or other species

Question 30

reproductive isolating mechanisms:

Answer 30

ie factors that prevent populations from reproducing successfully with one another - for new species to form then populations much be isolated long enough for mutations to accumulate

eg. geographic isolation, behavioural isolation

Question 31

comparing homologous and analogous structures

Answer 31

homologous structure = when classes share a common ancestor and then evolved into different forms (ADOPTIVE RADIATION)

analogous structures = a result of convergent evolution where different species evolve to resemble each other

Question 32

Are we a different species from chimpanzees?

Answer 32

Yes (even if there is a >2% difference) - this is because for us to have 99% the same DNA that is excluding at least 10% of DNA from humans and at least another 10% DNA from chimpanzee (only the same parts are noted)

Question 32

Are we a different species from chimpanzees?

Answer 32

Yes (even if there is a >2% difference) - this is because for us to have 99% the same DNA that is excluding at least 10% of DNA from humans and at least another 10% DNA from chimpanzee (only the same parts are noted)

Question 33

Define species

Answer 33

Species members have the ability to reproduce sexually producing fertile offspring with each other. They are genetically distinct.

Question 34

Define specification

Answer 34

The process by which new species form, whereby the new species are genetically distinct and is unable to reproduce successfully with the ancestral species

Question 35

Compare divergent evolution and spciation

Answer 35

Divergent evolution is where many species evolve from a common ancestor over millions of years. Speciation is the formation of a new species from an existing one as a result of reproductive isolation.

Question 36

Explain why the population need to become reproductively isolated before speciation can occur

Answer 36

They get isolated due to behavioural and/or geographical changes happening first, leading to genes no longer moving between the separated groups. Over this time the groups evolve and adopt to different environments to the pint where they can no longer breed

Question 37

variation across a range - GRADE

Answer 37

A species may GRADE (how gradual change) in phenotype over a geographic area

Question 38

variation across a range - CLINE

Answer 38

Continuous gradual change = CLINE, often occours along the length of a country or continent

Question 39

All the populations are of the same species IF

Answer 39

they are capable of interbreeding

Question 40

Genetic compatibility of a species decreases as…

Answer 40

the genetic divergence between the distanced populations increase

Question 41

Reproductively isolated =

Answer 41

two populations will diverge to an extent where they can no longer interbreed if returned to a shared environment

Question 42

Speciation =

Answer 42

when 2 populations can no longer interbreed and produce fertile, viable offspring. They are considered to be separate species.